Liquid Ejecting Head Nozzle Substrate Bubble Entrainment
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Solution Overview
Problem
Nozzles formed by an etching process in liquid ejecting heads tend to have issues with bubble entrainment due to large diameter differences and step portions, leading to unstable ink ejection.
Innovation Solution
The nozzle substrate is designed with continuous nozzle sections having diameters that differ by 0.1 to 0.4 times the first diameter, ensuring successively larger diameters to minimize bubble entrainment and stabilize ink ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If nozzles are formed by an etching process with multiple cylindrical sections having different diameters, then dimensional accuracy of the nozzle is improved, but bubble entrainment occurs due to large diameter differences and step portions
Solution Approach 1:
The patent applies parameter changes by precisely controlling the diameter difference between adjacent nozzle sections to be within 0.05mm to 0.20mm. This quantitative parameter optimization resolves the contradiction by maintaining the multi-section structure for dimensional accuracy while limiting the diameter difference to prevent bubble entrainment at step portions.
Solution Approach 2:
The patent applies local quality by making each nozzle section have a specific diameter within a controlled range, where the diameter difference between adjacent sections is locally optimized. This ensures that each local region (nozzle section) contributes to both the overall dimensional accuracy and the prevention of bubble entrainment at its boundaries.
2Reliability
If the diameter difference between nozzle sections is large, then the ink-ejecting characteristic is improved by considering flow-path resistance and inertance, but complex flow patterns and vortices occur near step portions
Solution Approach 1:
The patent optimizes the diameter parameter of each nozzle section by limiting the diameter difference to 0.05mm to 0.20mm between adjacent sections. This parameter control maintains the flow-path resistance and inertance characteristics needed for reliable ink ejection while preventing the formation of complex vortices and unstable flow patterns.
3Manufacturing precision
If a tapered portion is formed in the nozzle, then ink ejection precision is improved, but it is difficult to form such structure by etching process
Solution Approach 1:
The patent applies segmentation by dividing the tapered nozzle structure into multiple cylindrical sections with gradually increasing diameters. This segmentation allows the complex tapered shape to be formed using simple etching processes while maintaining the ink ejection precision that a continuous tapered portion would provide.
Solution Approach 2:
The patent uses a series of cylindrical sections with gradually changing diameters to approximate the curved tapered profile. This approach achieves the smooth transition of a tapered structure through discrete cylindrical segments that are easier to manufacture by etching while maintaining the desired ink flow characteristics.
Data Source
AI summary
A liquid ejecting head has a nozzle substrate made of crystalline material, in which a nozzle through which liquid is ejected is provided by an etching process. The nozzle includes a plurality of continuous nozzle sections having different diameters arranged coaxially in the direction of the thickness of the crystalline material. The nozzle sections include a first nozzle section that is located at the ejection-side end and that has a first diameter, and a second nozzle section that is continuous with the first nozzle section and that has a second diameter larger than the first diameter. The difference between the first diameter and the second diameter is not less than 0.1 and not greater than 0.4 relative to the first diameter.